The Diagnosis column of The New York Times Magazine regularly asks Well readers to take on a difficult case and try to solve a diagnostic riddle. This month, you’ll find details about a patient who comes to the hospital with three terrible lesions on her leg that don’t respond to the usual treatment. You will also have access to the notes from the doctors who saw the patient and test results that provide you with the same information that the doctors who originally encountered this medical mystery had.

The first reader to offer the correct diagnosis gets a signed copy of my book “Every Patient Tells a Story” and the satisfaction of solving a case that could have given Gregory House a run for his money. Let’s get started.

The Presenting Problem

A 54-year-old woman comes to the emergency room with sores on her left leg that have been worsening for a month.

The Patient’s Story

The middle-aged woman was inspecting her leg when her roommate walked into the room. “Wow, that looks a lot worse,” he told her. “A whole lot worse.”

The woman looked at the large wounds on the back of her calf and nodded. Over the past week or so they had gotten much larger, and they were terribly painful. Just changing the bandage was excruciating, though she made herself do it every day.

“You need to go to the emergency room,” her roommate persisted. Tomorrow, she told him, definitely tomorrow. “No,” he said firmly, “we need to go now.”

And so, half an hour later the woman found herself in the emergency room of Waterbury Hospital in Connecticut, unwrapping her wounded calf for the young nurse staffing the triage desk. The nurse gasped as the leg was exposed.

The back of the woman’s calf was dominated by a sore larger than a hockey puck and shaped like the continent of Africa. Two smaller lesions flanked it. Their edges were red and angry-looking. The largest wound’s center was invisible behind a layer of purulent fluid that covered the wound and drenched the bandage. “Don’t touch it,” the woman said, sounding almost childlike in her pain and fear.

The nurse excused herself and returned with a doctor. This was an infection that would need intravenous antibiotics, he agreed after a quick look at the leg. The woman needed to be admitted to the hospital. The patient nodded in agreement. This was her first visit to a hospital in over a decade. She hated doctors and feared hospitals. But she knew that she needed to be here.

You can read the emergency department triage report and doctor’s note below.

The Doctor’s Story

Dr. Nadine Stanojevic, an internal medicine resident in her third and last year of training, called out to the medical student on duty after the emergency room doctor had filled her in. They headed down the stairs to the E.R., where they found the patient in the large treatment room on a stretcher, separated from the other patients by long white curtains. The woman was sitting up, hunched over her leg like a mother bird protecting a fledgling. Dr. Stanojevic introduced herself and the medical student, then asked about her leg.

It had all started about a month ago, the patient told them, after a painful red bump appeared on the back of her leg. She’d had other lesions like this over the past year — small, painful abscesses that would appear on her arms or legs, then open and drain and slowly heal. A similar, smaller one had appeared on her arm. But this new leg thing — this was crazy.

Initially there was just one lesion. It opened and drained, but instead of resolving as these lesions usually did, it had gotten larger and larger. The two other lesions started just a few days later. She washed the wounds every day and put antibiotic cream and sterile bandages on them, but it didn’t seem to help. She changed creams. Still, they just continued to get bigger.

And the wounds themselves were exquisitely tender. The back of her calf felt like it was on fire. She hadn’t been able to leave the house to go to her office for the past couple of weeks because of the pain. Now, even standing was excruciating.

Dr. Stanojevic could see the toll the lesions had taken on the woman. She’d clearly lost a lot of weight — the skin on her face seemed to be a couple of sizes too large, making her dark eyes look huge. Her graying hair fell in messy curls around her bony face. Neglected remnants of colorful polish streaked across her nails.

As the young doctor watched the woman slowly peel a now saturated gauze pad from around her leg, a smell suggestive of unwashed feet — the scent of pus — seeped into the room. The wound itself was horrific.

More of the Patient’s Story

Although the patient hadn’t been to see a doctor in years, she had several medical problems. She was a recovering heroin addict, participating in a methadone program to stay sober. She had high blood pressure that was well controlled with a single medication (prescribed at the methadone clinic) and arthritis in her hands, knees and feet that required daily doses of ibuprofen. An H.I.V. test done at the clinic six months earlier had come back negative. And though she’d never been tested for hepatitis C, she figured that — like almost everyone she knew — she probably had it.

Photo

The patient's hands.Credit

On exam, the patient didn’t have a fever, and her blood pressure was normal. Her fingers were red and so swollen that the creases in the knuckles were almost invisible. (You can see pictures of her hands here.) On her left shoulder was a small abscess that was hot to the touch and tender.

The E.R. doctor had ordered a slew of labs. (You can see the laboratory results here.)

The patient was mildly anemic, though her white blood count was normal. Hepatitis serologies and an H.I.V. test had been sent, but the results were pending. Blood and wound cultures were sent.

The E.R. doctor had already started her on vancomycin, a powerful antibiotic, for a presumed infection with methicillin-resistant Staphylococcus aureus, or MRSA, a virulent bacterium that can cause abscesses and is resistant to most antibiotics. Dr. Stanojevic and the medical student discussed adding a second antibiotic but, like the E.R. doctor, decided MRSA was the most likely cause of this kind of terrible skin infection.

Dr. Stanojevic asked the surgeons to see the patient, in case the wound needed to be surgically cleaned. And she ordered an X-ray and an M.R.I. to see if the wound had infected the bone beneath. Then her beeper went off, and she and the student left the patient to see their next admission.

You can read Dr. Stanojevic’s admission note here.

A Stalled Recovery

The next day, Dr. Stanojevic thought the wounds looked a little better. The surgeons had cleaned off the yellow discharge, and the bottom of the shallow ulcer could be seen. It was red and angry-looking. The two smaller lesions were partly covered with dark scabs. (You can see what the lesions looked like — be warned: they are hard to look at — here and here.)

The young doctor was relieved to see that there was no evidence that the underlying muscle or bone was involved. But the next day, the patient’s third day in the hospital, the young doctor began to worry.

The wound looked no better, even though the patient had been on antibiotics for 48 hours. Maybe it wasn’t the right antibiotic. Normally, cultures grown from a sample of the wound would reveal the bacterial culprit and identify the antibiotic that would work best. But strangely, neither the blood culture nor the wound culture had grown out anything. Dr. Stanojevic expected to see Staph aureus because normally, Staph grows rapidly in the nutrient-filled culture dishes, but not this time. Why not? If it wasn’t MRSA, what could be eating away this woman’s leg like this?

You can review the M.R.I. and X-ray reports here.

You can review the follow-up laboratory results here.

Solving the Mystery

Now it’s your turn. Can you solve this mystery? Dr. Stanojevic did. I’ll post the answer on Friday.

Rules and Regulations:Post your questions and diagnosis in the Comments section below. The correct answer will appear Friday on Well. The winner will be contacted. Reader comments may also appear in a coming issue of The New York Times Magazine.